Devices that provide suction and irrigation to body cavities during surgery are well known in the art. Often, suction and irrigation are both performed through the same device. Therefore, while the instant invention relates particularly to the suction capabilities of the device, it should be noted that irrigation through the device is possible as well.
In its most basic form surgical suction of bodily fluids is accomplished through the use of a simple open ended tube, or cannula, with one end connected to a suction means and the other end placed inside the body cavity. A problem with this simple tube device arises when body tissue comes into contact with the hole in the end of the tube, known as the suction port. The tissue is sucked into the suction port thereby closing off the tube. Thus, the vacuum inside the tube increases and the operator must then either forcibly pull the tube away from the tissue, possibly harming the tissue, or shut off the suction to the tube and allow the pressure to equalize through normal leakage in the system thereby releasing the tissue. Shutting off the suction requires the user's attention, and waiting for pressure equalization delays the operation.
In order to alleviate these problems several prior art devices provide a plurality of additional holes in the tube to vent the tube if the suction port becomes obstructed. These holes are generally located in the wall of the tube near the suction port. However, because these additional holes are always open, they decrease the suction power at the suction port and therefore reduce the effectiveness of the device. To reduce the loss of suction power Brownlie et al., U.S. Pat. No. 4,487,600, discloses a device which allows the operator to remotely open or close selected side ports via the use of a small, imperforate tube which is adjustably positioned within a slightly larger perforated tube. Takahashi, U.S. Pat. No. 5,057,080, provides another mechanism to manually control the amount of venting provided to the tube and thus control the amount of suction at the suction port. Takahashi utilizes a tube made from soft material having only a main port. A single cut made in a portion of the tube is used to relieve the vacuum pressure by bending the tube to allow the cut to open. When the tube is straightened the cut is closed and suction is performed at the main port. While these manual venting mechanisms reduce the delay for the pressure to equalize, they nevertheless require the user's attention and manipulation, thereby reducing the user's efficiency during the operation.
Further, to avoid irritation of fragile body tissue, modern prior art suction devices are typically made with a soft flexible tip permanently attached to a more rigid tubing for ease of insertion. The tip is permanently attached to prevent accidental detachment while the device is manipulated in use. A deficiency in this design is that the entire assembly of the tubing and tip must be discarded after use, since the soft flexible tip cannot be easily sterilized. Thus, the unit is expensive to purchase and expensive to dispose of because of high medical waste disposal costs.